1 research outputs found
Interfacial Activation of <i>Candida antarctica</i> Lipase B: Combined Evidence from Experiment and Simulation
Lipase immobilization is frequently
used for altering the catalytic
properties of these industrially used enzymes. Many lipases bind strongly
to hydrophobic surfaces where they undergo interfacial activation. <i>Candida antarctica</i> lipase B (CalB), one of the most commonly
used biocatalysts, is frequently discussed as an atypical lipase lacking
interfacial activation. Here we show that CalB displays an enhanced
catalytic rate for large, bulky substrates when adsorbed to a hydrophobic
interface composed of densely packed alkyl chains. We attribute this
increased activity of more than 7-fold to a conformational change
that yields a more open active site. This hypothesis is supported
by molecular dynamics simulations that show a high mobility for a
small “lid” (helix α5) close to the active site.
Molecular docking calculations confirm that a highly open conformation
of this helix is required for binding large, bulky substrates and
that this conformation is favored in a hydrophobic environment. Taken
together, our combined approach provides clear evidence for the interfacial
activation of CalB on highly hydrophobic surfaces. In contrast to
other lipases, however, the conformational change only affects large,
bulky substrates, leading to the conclusion that CalB acts like an
esterase for small substrates and as a lipase for substrates with
large alcohol substituents